Broadcasting and telecommunications have historically occupied separate fields. In the past, broadcasting was largely an “over-the-air” medium while wired media carried telecommunications. That distinction may no longer apply as both broadcasting and telecommunications may be delivered over either wired or wireless media. Present development may adapt broadcasting to mobility services. One limitation has been that broadcasting may often require high bit rate data transmission at rates higher than could be supported by existing mobile communications networks.
Terrestrial television and radio broadcast networks have made use of high power transmitters covering broad service areas, which enable one-way distribution of content to user equipment such as televisions and radios. By contrast, wireless telecommunications networks have made use of low power transmitters, which have covered relatively small areas known as “cells”. Unlike broadcast networks, wireless networks may be adapted to provide two-way interactive services between users of user equipment such as telephones and computer equipment.
Standards for digital television terrestrial broadcasting (DTTB) have evolved around the world with different systems being adopted in different regions. The three leading DTTB systems are, the advanced standards technical committee (ATSC) system, the digital video broadcast terrestrial (DVB-T) system, and the integrated service digital broadcasting terrestrial (ISDB-T) system. The ATSC system has largely been adopted in North America, South America, Taiwan, and South Korea. This system adapts trellis coding and 8-level vestigial sideband (8-VSB) modulation. The DVB-T system has largely been adopted in Europe, the Middle East, Australia, as well as parts of Africa and parts of Asia. The DVB-T system adapts coded orthogonal frequency division multiplexing (COFDM). The ISDB-T system has been adopted in Japan and adapts bandwidth segmented transmission orthogonal frequency division multiplexing (BST-OFDM).
While 3G systems are evolving to provide integrated voice, multimedia, and data services to mobile user equipment, there may be compelling reasons for adapting DTTB systems for this purpose. One of the more notable reasons may be the high data rates that may be supported in DTTB systems. For example, DVB-T may support data rates of 15 Mbits/s in an 8 MHz channel in a wide area single frequency network (SFN). There are also significant challenges in deploying broadcast services to mobile user equipment. Because of form factor constraints, many handheld portable devices, for example, may require that PCB area be minimized and that services consume minimum power to extend battery life to a level that may be acceptable to users. Another consideration is the Doppler effect in moving user equipment, which may cause inter-symbol interference in received signals. Among the three major DTTB systems, ISDB-T was originally designed to support broadcast services to mobile user equipment. While DVB-T may not have been originally designed to support mobility broadcast services, a number of adaptations have been made to provide support for mobile broadcast capability. The adaptation of DVB-T to mobile broadcasting is commonly known as DVB handheld (DVB-H). The broadcasting frequencies for Europe are in UHF (bands IV/V) and in the US, the 1670-1675 MHz band that has been allocated for DVB-H operation. Additional spectrum is expected to be allocated in the L-band world-wide.
The DVB-S2 is a second generation standard for satellite broadband applications, developed by the digital video broadcasting (DVB) project. The DVB-S2 standard may be enabled to support quadrature phase shift keying (QPSK), 8PSK, 16 phase asymmetric phase shift keying (16APSK), and 32APSK modulation systems. The DVB-S2 standard may be enabled to transport single or multiple streams in a variety of formats, for example, MPEG-2 transport streams and each stream may be protected in a different manner.
Communication systems may employ coding to ensure reliable communication across noisy communication channels. These communication channels may exhibit a fixed capacity that may be expressed in terms of bits per symbol at a certain signal to noise ratio (SNR), defining a theoretical upper limit known as the Shannon limit. As a result, coding design has aimed to achieve rates approaching this Shannon limit. One such class of codes that approach the Shannon limit is low density parity check (LDPC) codes.
The LDPC encoding technique may be highly complex and its generator matrix may require storing a very large, non-sparse matrix. From an implementation perspective, a key challenge in LDPC code implementation may include achieving a connection network between several processing nodes in a decoder. Further, the computational load in the decoding process, specifically the check node operations may pose problems or challenges such as performance, complexity and storage requirements.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.